Pulsator for hydraulic systems controlling actuating mechanisms

ABSTRACT

In the housing of a pulsator are accommodated a delivery valve and on its opposite ends, a rigidly connected pusher serving for opening the valve and an air cylinder for actuating said valve at its closing coaxially mounted relative thereto. A cavity between the pusher and the delivery valve is constantly connected to a high-pressure main and to an actuating mechanism, a cavity above the valve being connected to a drain main, with a cavity below the pusher being connected to the high-pressure main via a non-return valve, and to a liquid drain main via a valve unit provided with a throttle. The valve unit allows the cavity below the pusher to be completely shut off when the valve is raised and to place it in communication with the liquid drain main when the valve is lowered, which, in turn, increases the high-speed response of the valve, and hence, the number of pulsations per unit of time.

United States atent 1 1 Goryainov et al.

[ Dec. 3, 1974 PULSATOR FOR HYDRAULIC SYSTEMS CONTROLLING ACTUATINGMECHANISMS [76] Inventors: Vladimir lvanovich Goryainov, 50,

kv. 2 p/o Chelobatievo, Mytischnsky raion, Moskovskaya Oblast; IvanVasilievich Kononov, 40, kv. 4 ulitsa Torpedo, Vorenezh; Ivan EgorovichMaslennikov, 26, kv. 82 ulitsa Druzhinnikov, Vorenezh; VladimirNikiforovich Platonov, ulitsa 9 Yanvarya 49, kv. 45, Vorenezh;Vyacheslav Evgenievich Popov, ulitsa Peshe Streletskaya 125, kv. 76,Vorenezh, all of USSR.

[22] Filed: Feb. 13, 1973 [21] Appl. No.: 332,152

[52] US. Cl. 137/624.14, 91/50 [51] Int. Cl F011 9/02 [58] Field ofSearch 91/50; 137/624.13, 624.14,

[56] References Cited UNITED STATES PATENTS 2,378,979 6/1945 Burt 91/50X 3,141,384 7/1964 Hoffman 91/50 X 3,345,915 10/1967 Dotto 137/624.l4 xFOREIGN PATENTS OR APPLICATIONS 1,309,903 10/1962 France l37/624.l41,225,496- 9/1966 Germany 91/50 Primary Examiner-William R. ClineAssistant ExaminerGerald A. Michalsky Attorney, Agent, or FirmHolman &Stern [5 7] ABSTRACT In the housing of a pulsator are accommodated adelivery valve and on its opposite ends, a rigidly connected pusherserving for opening the valve and an air cylinder for actuating saidvalve at its closing coaxially mounted relative thereto.

A cavity between the pusher and the delivery valve is constantlyconnected to a high-pressure main and to an actuating mechanism, acavity above the valve being connected to a drain main, with a cavitybelow the pusher being connected to the high-pressure main via anon-return valve, and to a liquid drain main via a valve unit providedwith a throttle. The valve unit allows the cavity below the'pusher to becompletely shut off when the valve is raised and to place it incommunication with the liquid drain main when the valve is lowered,which, in turn, increases the high-speed response of the valve, andhence, the number of pulsations per unit of time.

3 Claims, 1 Drawing Figure BACKGROUND OF THE INVENTION The presentinvention relates to devices producing pulsating loads in hydraulicsystems controlling actuating mechanisms. 7

It is advantageous to utilize the pulsator, realized according to thepresent invention, in the forge-press machine-building industry, and inparticular, in presses PRIOR ART Known in the art are pulsators forhydraulic systems controlling actuating mechanisms of hydraulic presses.The housings of such pulsators accomodate a delivery valve and mountedcoaxially with said valve, on its opposite ends, an air cylinder and apusher adapted to actuate the delivery valve in closing and opening,respectively.

Said elements form cavities, in combination with I each other and thehousing, constantly communicating with the hydraulic system mains. Thecavity defined between the delivery valve and the pusher permanentlycommunicates with a high-pressure main and with actuating mechanisms;the cavity above the delivery valve communicates with a liquid drainmain; the cavity below the pusher communicates with the high-pressuremain via a non-return valve, and with the liquid drain main, via apipeline equipped with a throttle.

The delivery valve of pulsators is in a contacting arrangement with thepusher due to its being loaded by a spring, with the latter operating inthe oscillating duty with a frequency of several cycles per second andan oscillation amplitude equal to the valve opening stroke.

In said pulsators the closing time of the delivery valve, and also, thatof the pusher and movable component of the air cylinder depends on theflow crosssection of the throttle mounted on a pipeline connecting thecavity below the pusher to the drain main. The larger the throttle flowcross-section, the less time is required for closing the delivery valve,which contributes to increasing the'oscillation frequency and hence, thepulsator efficiency. However, the flow cross-section of said throttleshould be such as to ensure, at the instant the delivery valve opens, apressure drop between the cavity below the pusher and the cavity betweenthe latter and the delivery valve, sufficient for displacing the movableelements.

In other words, in order to effect quick closing of the delivery valve,the throttle flow cross-section should be these pulsators in hydraulicsystems whose actuating mechanisms develop forces exceeding 200 to 300t,

(ton force), with the liquid consumption exceeding 300 l/min, it isimpossible to obtain an oscillation frequency higher than 10 to 15c.p.s.

The constantly communicating cavity below the pusher with the drain mainaffects adversely the pulsator operation, since with the delivery valveopening a portion of compressed liquid is lost (up to percent), whichaffects the pulsator efficiency.

A further drawback of the known pulsators is also in thatv the contactbetween the delivery valve and the pusher is ensured by means of aspring disposed in the cavity below the pusher. In order to ensurenormal operation of the pulsator with said means effecting contactbetween the valve and the pusher, it is necessary that the pressure riseof liquid per cycle be effected at the same speed both in the cavitybelow the pusher and the cavity between the pusher and delivery valve,i.e., the resistances of pipelines connecting said cavities should beequal.

Such a condition cannot be achieved in practice, since the pipelineconnecting the cavity below the pusher to the high-pressure main mountsa non-return valve adjusted to a pressure drop exceeding 10 kgf/cm, atwhich the spring force is insufficient to ensure reliable contactbetween the valve and the pusher at the instant the cavities are filledwith liquid, resulting in the pusher parting from the valve, therebydisturbing the operating duty.

To ensure constant contact between the valve and the pusher, a spring,whose force exceeds that exerted by the pressure drop should beprovided.

In practice the spring force exceeds 1,000 kgf, taking into account theadditional resistance in the pipeline. With the system operating in anoscillating duty at a frequency of several cycles per second, this tendsto decrease sharply the durability of the spring, and hence,

large, while in order to ensure the required pressure drop, saidcross-section should be as small as possible, or equal to zero.

Practically, the closing time of the delivery valve constituteshundredths of a second, and hence when using the reliability of thepulsator.

Independent connection of the delivery valve and the pusher involves aconsiderable increase in the pulsator sizes, on the one band, due to alarge flow cross-section of the delivery valve and diameter of thepipeline connecting the cavity below the pusher to the highpressuremain, and, on the other hand, due to the fact that the air cylinderforce should exceed the spring force below the pusher.

In addition, well known in the art are slide-valve type pulsators forhydraulic systems controlling actuating mechanisms. 1 v

The principal component in these pulsators is a movable element (a slidevalve or a disk) disposed in the pulsator housing and adapted to bedisplaced by an individual drive according to a preset law actuated.Ports (holes) provided in the slide valve and the housing are matched inthe course of operation and communicate the actuating mechanismsalternately with the highpressure main and with the drain main.

Pulsators of the slide-valve type have the following drawbacks:

the slide valve ports fail to be opened in synchronism with the supplyof liquid delivered by the high-pressure main;

constant leaks of the working fluid as a result of failure to ensurecomplete leak-tightness of the slide valve;

usage of mineral oil as the working fluid possessing a relatively lowmodulus of elasticity, which reduces the hydraulic system efficiency atpulsating loads due to excessive energy losses for compressing thefluid; and

more stringent requirements placed upon oil cleanliness, since evenminor contamination leads to rapid wear of the rubbing surfaces,increases leaks and shorter service life of the pulsator.

Widely known are also plunger-type pulsators for hydraulic systemscontrolling actuating mechanisms, wherein a plunger serves as themovable element producing pulsations of the liquid pressure.

Such a plunger receives the reciprocating motion from an eccentricmechanism or a cam mechanism set in rotation by individual motors.

A principal drawback of the plunger-type pulsator is failure to providea reliable, high-speed and relatively powerful drive (eccentric-plungerlink), required for feeding the required volume of fluid (100 to 500 cmper pulse at a speed of 1,000 to 1,500 rpm). Moreover, said pulsatorsfail to ensure the required parameters of the hydraulic system, since,for example, the fluid pressure, oscillation amplitude, etc., aredependent on the volume of the fluid delivered by the plunger during onestroke.

OBJECTS AND SUMMARY OF THE INVENTION It is an object of the presentinvention to ensure a highspeed response of the delivery valve duringits opening and closing and to obtain, respectively, high pulsationfrequency.

Another object of the present invention is to provide a required flowrate of the delivery valve, making it possible to construct hydraulicsystems having largercapacity actuating mechanisms with a higherfrequency of pulsating loads.

Still another object of the present invention is to ensureleak-tightness of pulsator cavities subjected to high pressures.

A further object of the invention is to obtain simplicity andconvenience in manipulating the pulsator.

It is advantageous that the valve unit be provided with a housingaccommodating a spring-loaded movable element defined by a cylinder,whose side surface provides, in combination with the housing, an annularchamber communicating with the cavity below the pusher, while whose endsurface provides, in combination with the housing, a chambercommunicating with the drain main, with the end surfaces of the movableelement comprising an end piece adapted to interact with the'movableelement of the air cylinder.

Such a design of the valve unit makes it possible to reliably seal thecavity below the pusher as the delivery valve is opened and tocomparatively quickly drain the liquid from the cavity below the pusheras the delivery valve is closed. Besides, such a construction isreliable in service and ensures a long service life.

It is also advantageous to mount in the cavity above the delivery valve,a piston having a cross-sectional area somewhat exceeding that of thedelivery valve and to adapt the end surfaces of said piston forinteraction with the delivery valve and movable element of the aircylinder, respectively.

The installation of the piston in the cavity above the delivery valvemakes it possible to utilize the energy of the liquid stream dischargedto drain, which is conducive to complete opening of the delivery valve.

A pulsator for hydraulic systems controlling actuating mechanismsembodying the present invention al- Yet another object of the inventionis to ensure reliability and longevity of the pulsator.

In accordance with the invention, a pulsator for hydraulic systemscontrolling actuating mechanisms is provided in whose housing aredisposed a delivery valve and mounted coaxially with said valve, on itsopposite ends, a controlled air cylinder and a pusher, adapted toactuate the delivery valve in closing and opening, respectively, thecavity between the delivery valve and the pusher constantlycommunicating with a high-pressure main and with an actuating mechanism,the cavity above the delivery valve communicating with the liquid drainmain, the cavity below the pusher communicating with the high-pressuremain via a nonreturn valve, and with the liquid drain main via apipeline with a throttle, wherein, according to the invention, apipeline connecting the cavity below the pusher to the liquid drain mainmounts, ahead of the throttle, a valve unit, whose movable element isadapted to shut ofi' said pipeline as the delivery valve is opened, andto be actuated by a movable element of the air cylinder at the end ofthe delivery valve stroke during its opening, in order to connect thepipeline to the liquid drain main as the delivery valve is closed, withthe delivery valve and the pusher being rigidly interconnected.

lows for the required quick response of the delivery valve to beobtained at its actuation.

Moreover, a higher flow rate when draining the liquid from the system isensured, since such a design of the pulsator makes it possible toincrease the delivery valve and pusher sizes, reducing, at the sametime, the volumes of respective cavities.

The advantages of the pulsator hereinabove described permit itsutilization in hydraulic systems comprising actuating elements whichdevelop a force of from to 2,000 t (ton force) with high frequencies ofpulsating loads (up to 30 50 c.p.s.).

BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be explained ingreater detail withreference to an embodiment thereof which isrepresented in the accompanying drawing, in which the sole FIGURE is aschematic representation of a pulsator for hydraulic systems controllingan actuating element.

DETAILED DESCRIPTION OF THE INVENTION The pulsator has a housing 1accommodating a delivery valve 2 and a pusher 3, mounted in coaxialrelationship.

The housing 1, valve 2 and pusher 3 define a cavity 4 and a cavity 5below the end face of the pusher 3.

To overcome any forces caused by the pressure drop in the cavities 4 and5, for actuating the pusher 3, and for ensuring constant contact of thepusher 3 with the valve 2, the pusher and valve are interconnectedrigidly by means of an end piece 6 provided with a supporting washer 7,fixed in the end face of the delivery valve 2 and passing through anaxial hole in the bottom of the pusher 3.

Above the end face of the delivery valve 2, on the end opposite to thepusher 3 is located a cavity 8 which communicates with a drain main 10through a pipeline 9.

To utilize the energy of the liquid stream discharged to drain, thecavity 8 accommodates a piston 1 1, whose area is greater than that ofthe delivery valve 2. The piston 11 has an end piece or extension 12which thrusts against theend face of the delivery valve 2. I

Above the piston ll is disposed an air cylinder 13 having a movablemember 14 mounted coaxially with the valve 2. The movable member is apiston provided with a rod 15 and end piece 16 secured to its endsurfaces. The end piece 16 serves for imparting the force exerted by theair cylinder 13 via the piston 11 to the delivery valve 2.

The cavity 4 between the valve 2 and pusher 3 communicates with a pump18 via a high-pressure main 17, and with an actuating mechanism (notshown) via a pipeline 19.

The cavity 5 below the pusher 3 communicates with the high-pressure main17 via a non-return valve 20, and with the drain main via a pipeline 21,a valve unit 22 and a throttle 23.

The valve unit 22 has a housing 24 and a movable element 25 thereindisposed, defined as a cylinder, whose side surface provides, incombination with the housing 24, an annular chamber 26 communicatingwith the cavity 5 below the pusher.

The end surface of said movable element 25 forms, in combination withthe housing 24, a chamber 27 communicating with the drain main 10 viathe throttle 23.

The movable element 25 has an end piece 28 secured in its end face whichis adapted to interact with the rod at the end of the opening stroke ofthe valve 2 in order to ensure its quick closing.

To ensure a quick lowering of the movable element 25, i.e., shutting offthe chambers 26 and 27, the element is loaded by a spring 29 whose forcecan be adjusted by a screw 30.

Due to the fact that the chamber 26, and hence the cavity 5 areleak-proof and that the cavity can communicate with the drain main 10via a larger flow crosssection as the valve 2 is closed, the lattersizes can be relatively large, depending on the liquid flow rate.

The force exerted onto the delivery valve 2 and hence, the liquidpressure in the main 17 and in the other cavities under high pressure,is adjusted with the help of the air cylinder 13, which communicateswith an air main 34 via an air distributor 31, non-retum valve 32 and areducing valve 33.

The pulsator for hydraulic systems controlling actuating mechanismsoperates as follows:

The pump 18 incorporated in the high-pressure main 17 is started. Withno force exerted onto the piston 14, the cavities 4 and 8 areinterconnected, allowing the liquid to flow freely into the drain main10.

For placing the pulsator into operation, air from the air main 34 isadmitted into the cylinder 13 via the reducing valve 33, non-returnvalve 32 and air distributor 31, thus exerting a force onto the piston14 and delivery valve 2. The liquid starts flowing from the pump 18 intothe cavity 4 to the actuating mechanism, and into the cavity 5 andchamber 26 via the non-retum valve 20.

As the resistance in the actuating mechanism starts building up, thepressure in the hydraulic system starts rising until it reaches a valuecorresponding to the force exerted on the valve 2 by the air cylinderl3.

As the pressure in the cavity 4 exceeds the force exerted by the aircylinder 13, the valve 2 opens slightly, due to which the excesspressure is relieved from the cavity 5, high-pressure main 17 andactuating mechanism. A pressure differential is produced between thecavities 4 and 5, determined by the liquid volume compressed in thecavity 5 and provided for by the nonreturn valve 20.

Due to the pressure difference and simultaneous actuation of the piston11 by the liquid stream discharged to drain, the pusher 3 starts liftingthe valve 2 until the total force developed below the pusher 3 andpiston 11 and the force exerted onto the piston 14 of the air cylinder13 become equal.

The movable element 25 is so disposed in the housing 24 that theclearance between its end piece 28 and the rod 15 is less than thepossible opening stroke of the delivery valve 2. In this case, at theend of the stroke, the piston 14 actuates the end piece 28 with the aidof its rod 15 and opens slightly the movable element 25. A pressure ofliquid is produced in the chamber 27 by means of the throttle 23, due towhich the movable element 25 opens completely and provides communicationbetween the chambers 26 and 27.

During this time the pressure in the cavity 4, main 17 and the actuatingmechanism will be completely relieved.

At the moment the movable element 25 of the valve unit 22 is raised, thevalve 2 closes quickly, discharging the liquid from the cavity 5 withthe help of the pusher 3 along the pipeline 21 into the drain main 10via the chambers 26, 27 and throttle 23.

Following the complete drain of the liquid from the cavity 5, themovable element 25, under the action of the spring 29 (whose tension isadjusted with the help of the screw 30) closes, and the cycle isrepeated.

In this way the pressure is produced and relieved automatically, whichresults in a pulsating load in the actuating mechanism.

During the time the chamber 26 communicates with the drain main 10, theliquid from the main 17 is not supplied into the cavity 5 due to thepressure difference produced by the non-retum valve 20.

In order to overcome the forces caused by said pressure differenceacting on the pusher 3 via the delivery valve 2, and to ensure aconstant contact between the pusher 3 and the valve 2, a rigidinterconnection is provided between the end piece 6 with the supportingwasher 7.

The pressure in the hydraulic system is adjusted by means of the aircylinder l3 through the reducing valve 33. For convenient control of thepulsator, the valve 33 can be mounted, for example, on a control panel(not shown).

The time required for the movable parts of the pulsator to perform acycle and hence, the liquid pulsation frequency, is adjusted by means ofthe throttle 23. Taking into account that at the instant the valve 2opens the cavity 5 is rendered leak-proof, e.g., shut off from the drainmain 10, the flow cross-section of the throttle I 23 can be taken in thepresent embodiment considerably larger, as compared with knownpulsators, and be adjusted over a wide range.

Pilot samples of the pulsators executed according to thepresentinvention have been mounted in hydraulic presses effecting to 500t (ton force) pulsating loads and are undergoing experimental-industrialoperation.

The oscillation frequency of actuating mechanisms (press plungers)constitutes to c.p.s. at an amplitude of up to 1 mm.

What is claimed is:

l. A pulsator for hydraulic systems controlling actuating mechanismscomprising: a housing; a delivery valve disposed in said housing; an aircylinder having a movable element and adapted for closing said valve,said air cylinder being disposed in said housing coaxially with saiddelivery valve at one of its ends; a pusher rigidly connected to saiddelivery valve disposed in said housing coaxially with said valve at itsopposite end and serving for opening said delivery valve; a first cavitybetween said delivery valve and pusher, permanently communicating with ahigh-pressure main of the hydraulic system and with an actuatingmechanism; a second cavity above the valve, communicating with a liquiddrain main of the hydraulicsystem; a third cavity below said pusher;pipelines for connecting said third cavity to said high-pressure anddrain mains, respectively; a non-return valve mounted on said pipelineconnecting said third cavity to said high pressure main; a throttlemounted on said pipeline connecting the third cavity to said liquiddrain main; a valve unit having a movable element mounted on saidpipeline ahead of said throttle; the movable element of said valve unitserving to shut off said pipeline as said delivery valve is opened andto be actuated by the movable element of said air cylinder at the end ofthe delivery valve opening stroke in order to connect said pipeline tosaid liquid drain main as the delivery valve is closed.

2. The pulsator as claimed in claim 1, wherein said valve unit isprovided with a housing and having disposed therein said movable elementwhich is spring loaded and defined by a cylinder, whose side surfaceforms, in combination with the housing, an annular chamber communicatingwith the third cavity, while the end surface forms, in combination withthe housing, a chamber communicating with the drain main, the movableelement having an end surface, and an end piece mounted on the endsurface for interacting with the movable element of the air cylinder.

3. The pulsator as claimed in claim 1, wherein a piston is accommodatedin the second cavity the crosssectional area of the piston beingsomewhat larger than that of the delivery valve, the piston having endsurfaces adapted to interact with the delivery valve and the movableelement of the air cylinder, respectively.

1. A pulsator for hydraulic systems controlling actuating mechanismscomprising: a housing; a delivery valve disposed in said housing; an aircylinder having a movable element and adapted for closing said valve,said air cylinder being disposed in said housing coaxially with saiddelivery valve at one of its ends; a pusher rigidly connected to saiddelivery valve disposed in said housing coaxially with said valve at itsopposite end and serving for opening said delivery valve; a first cavitybetween said delivery valve and pusher, permanently communicating with ahigh-pressure main of the hydraulic system and with an actuatingmechanism; a second cavity above the valve, communicating with a liquiddrain main of the hydraulic system; a third cavity below said pusher;pipelines for connecting said third cavity to said high-pressure anddrain mains, respectively; a non-return valve mounted on said pipelineconnecting said third cavity to said high pressure main; a throttlemounted on said pipeline connecting the third cavity to said liquiddrain main; a valve unit having a movable element mounted on saidpipeline ahead of said throttle; the movable element of said valve unitserving to shut off said pipeline as said delivery valve is opened andto be actuated by the movable element of said air cylinder at the end ofthe delivery valve opening stroke in order to connect said pipeline tosaid liquid drain main as the delivery valve is closed.
 2. The pulsatoras claimed in claim 1, wherein said valve unit is provided with ahousing and having disposed therein said movable element which is springloaded and defined by a cylinder, whose side surface forms, incombination with the housing, an annular chamber communicating with thethird cavity, while the end surface forms, in combination with thehousing, a chamber communicating with the drain main, the movableelement having an end surface, and an end piece mounted on the endsurface for interacting with the movable element of the air cylinder. 3.The pulsator as claimed in claim 1, wherein a piston is accommodated inthe second cavity the cross-sectional area of the piston being somewhatlarger than that of the delivery valve, the piston having end surfacesadapted to interact with the delivery valve and the movable element ofthe air cylinder, respectively.